ok, I thought this might be interesting for you. since I conceded victory to MB yesterday and went all back to the basics of maya I can just tell you:
have a look at FBIK (Full Body Inverse Kinematic)
the docs pretty well cover everything you need to know. you can also import an FBIK Example to have a closer look at the setup. all goes easy and fast in maya and I must tell - besides the fact, that maya´s Character naming convention and also the Character´s behaviour is exactly the same as in MB - really nobody needs motionBuilder ever in his life with FBIK in my opinion.. which might change when I have some more practice with the matter. but as far as I can see maya has allmost the complete MotionBuilder Package integrated within a small menu (Skeleton -> Full Body IK). you even have animation retargeting functionality within mouse clicks like in MB where you feed one Character into another Control Rigg. honestly the really only thing that maya doesn´t come up with is animating in layers which would be the icing on the cake, but besides you can make use of the trax editor I allready found a plugin which adds animation layers to your GUI, which you can find there
well as far as I understand things now it would be completely ridicoulous in case you allready work with maya and have a good understanding of it (not being an animation artist only) to pay about 4500 Euros for an additional menuItem in maya called MotionBuilder or in maya terms - FullBodyIK. (which is btw twice expensive then maya complete itself)
I hope I could give you some usefull input on all of this. and in case you are obleged by any company or university to use motionBuilder I still would advice to have a look at FBIK in maya and read the docs on it, because it really made clear how things work together within this not-easy-character-setup.
all the best!
everything starts and ends in the right place at the right time.